The present invention constitutes an improvement in the development of combination labor, delivery and patient care beds. U.S. Pat. No. 4,139,917, issued on Feb. 20, 1979 shows a bed that includes a removable lower mattress section which can be rolled about the floor on independent casters. Various positions of the bed are illustrated in the patent to show its ability to serve as a patient care bed or operational chair during birthing procedures. While this bed has been commercially successful, its use requires accommodation to use of a separable mattress unit that requires storage space when not being utilized by the patient or by attending personnel.
A subsequent bed design is shown in U.S. Pat. No. 4,411,035, which was issued Oct. 25, 1983. In this bed, which has been produced and sold by the Borning Corporation of Spokane, Washington as the 650H-R (TM) Birth Chair/Child Bearing Bed, the lower mattress assembly is partially retractable under the seat when the seat is in a raised position. The retractable feature solves the problem of accommodating a separable bed assembly, but the prior mechanism dictates first raising the seat before retracting the foot section of the bed. This limits the bed positions in which the retractable feature can be utilized.
Another bed, introduced by the Borning Corporation as the Genesis (TM) Multipurpose Birthing Bed, provides an elevationally adjustable lower mattress assembly that can be lifted from the unit and removed when not desired. While much smaller than the separable foot section of the bed shown in U.S. Pat. No. 4,139,917, this removable section again requires external storage space.
The present invention has been designated to provide total versatility to the lower mattress assembly. It is not only removable, as in the Genesis (TM) unit, but can be recessed under the seat of the upper mattress assembly regardless of the seat position or the elevation of the bed with respect to the supporting floor. This has been accomplished by a combination of a novel nesting lift apparatus for the bed frame and novel outer supports that carry the lower mattress assembly while extended from the bed frame. The option of utilizing foot supports in place of, or in conjunction with the lower mattress assembly is provided by the outer supports movably mounted on the bed frame for powered elevational adjustment as required. The outer supports can be connected to powered brackets which carry elevational adjustable leg or foot supports. The extended lower mattress assembly is adapted to "piggyback" the brackets for the foot supports for powered elevational adjustment of the lower mattress. The lower mattress assembly can also be manually raised or lowered relative to the bed frame independently of the elevational position of the foot supports. The entire bed can also be shifted to a critical care mode, or Trendelenburg position, when this is desired. The result is an extremely versatile bed/chair for maternity and gynecological procedures.